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Cine Meter for iPhone: faq copyright © 2013-2014 Adam J. Wilt  
 
A light meter with a waveform monitor and a false-color picture
 
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I can't find Cine Meter in the App Store! Where is it?

Are you searching on an iPad running iOS 6 or later? By default, the App Store on iPad only shows iPad apps. Select “iPhone Apps” at the top of the screen, and Cine Meter should appear.

How do I manually set exposure and white balance?

I’m sorry, there is no manual mode: iDevice cameras don't allow it. Instead you have to lock the auto-exposure and auto-white-balance settings while looking at something with the proper exposure and white balance, like a gray card. See How To for details.

How big is the spot meter's spot?

It depends on your iDevice camera’s angle of view. On my iPod touch 4G, it’s about 10º.

Can I change the size of the spot metering area?

No, sorry. It’s set by the camera in your iDevice, and it isn't adjustable. 

Can Cine Meter measure color temperature?

No. iDevice cameras do not report any color temperature or white balance information other than "white balance locked" or "white balance unlocked", so there's no way to find out what the real color of the scene is.

Why doesn’t the light meter match my DSLR / handheld meter?

Cine Meter computes exposure based on the standard APEX equation, using the assumed EXIF values for K and N. Its default calibration matches my Spectra Pro IV and Gossen Starlite meters very closely. However, it may not match your meters:

Why no incident meter mode?

Incident readings require incident light sensors, which iDevices lack. Cine Meter uses the iDevice’s camera. Like any other camera, it's a reflected-light sensor.

In theory one could turn an iDevice camera into an incident sensor by mounting a spherical diffuser or photosphere — one of those ping-pong-ball-lookalike domes — in front of the camera, but that’s not something I can do in software alone. Cine Meter is for reflected light only.

You can shoot an 18% gray card with Cine Meter to get the same result as an incident meter would give you (though you may want to open up 1/2 stop from the reflected reading to match your incident meter’s reading).

Where’s the lux/footcandle reading?

It can’t be done with a reflected meter; not properly. Lux and footcandles are measures of light illuminating an object, not the light reflected from it.

The folks making Pocket Light Meter found that people were improperly using the lux/fc readouts in an early version of their app to judge emergency lighting installations and for other life-safety applications, so they had to take those measurements out. Let’s not go there...

Where is the Android version?

I haven’t written it yet! Android cameras (most of them, at least) don't provide brightness-value metadata, only camera-exposure metadata, making it much harder to calculate an accurate exposure value: camera exposure can vary by as much as a stop from the "correct" value depending on how the camera is programmed. However, I may have a workaround for that, though I'll need to test it before I can say for certain. Stay tuned...

Why isn't Cine Meter II a free upgrade or an in-app purchase for Cine Meter?

If you bought Cine Meter and are upset that Cine Meter II isn't free / an in-app upgrade, I'm sorry.

Why not?

It's not free because it took me time to make Cine Meter II, and I have rent and food and health insurance and suchlike to pay for (time spent working on apps is time I'm not spending doing paid work for clients). The profits from the original $5 Cine Meter in a very low-volume, narrow market segment simply don't allow for a lot of free upgrades, not unless I have the app display ads (which I refuse to do).

It's not an in-app purchase because of cost and liability issues related to in-app purchase patents. Adding in-app purchase incurs the cost, complications, and overhead of hiring a lawyer to work out the licensing agreement and paying the associated royalties (overhead which would result in higher app costs), and adds complexity to the code (which would have made it bigger, slower to start up, and later to market).

Instead I made Cine Meter II a separate app, an app priced so that I can afford to upgrade it for free... version 1.1 is waiting for review as we speak.

I'm a student: can I get a discount?

Both Cine Meter and Cine Meter II are eligible for the educational volume purchase program. Your school can buy 20 or more at half price, and give you a code to install it on your iDevice. Details at http://www.apple.com/education/it/vpp/

Why isn’t my question answered here?

Because I haven’t heard it yet, that's why. Ask me and I’ll see if I can answer it.



© 2013-2014 Adam J. Wilt.  Last updated 2014.07.27